A vex file extension is related to the VLBI experiment definition data format.
VEX file extension - VLBI experiment definition data
What is vex file? How to open vex files?
File type specification:
The vex file extension is associated with the very long baseline interferometry (VLBI), an astronomical interferometry used in radio astronomy.
The vex file stores experiment definition data format for the VLBI.
This vex file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.